This isn't a GEOS issue (or, maybe GEOS has a similar WKB interpretation issue), but anyway, I've decided to treat "polygon with a zero vertex ring" as "empty", in the same way "polygon with no rings" is empty. So the example query above will return true. As a side effect, you won't be able to round-trip WKB of the form 01030000000100000000000000. Instead if you put in 01030000000100000000000000 (polygon with one empty ring) you'll get out 010300000000000000 (polygon with no rings).